Introduction

Diagenesis involves both physical and chemical processes that act to modify sediment during burial and lithification as it is brought into a subsurface environment of increased pressure, temperature, and changing pore-fluid compositions. These processes bring about a variety of changes in sediment characteristics, including compaction and cementation (porosity loss), dissolution of framework grains and cements (porosity gain), mineral recrystallization, and mineral replacement (see review in Boggs, 1992, ch. 9). Diagenesis can decrease the capacity of sediments and sedimentary rocks to transmit and store economically significant quantities of petroleum, natural gas, and ground water, as well as adversely affecting our ability to make reliable interpretations of provenance and depositional environments. On the other hand, some diagenetic processes have a positive economic impact. For example, dissolution can increase porosity of sediments and thus their ability to store hydrocarbons. Diagenesis is considered such an important topic among sedimentologists that hundreds of articles and more than 15 full-length books about siliciclastic diagenesis have been published in the English language alone (see, for example, Burley and Worden, 2003).

Diagenetic minerals and fabrics are commonly studied by using a variety of petrographic and geochemical techniques. Cathodoluminescence imaging is also making important contributions to our understanding of diagenetic processes and our ability to recognize diagenetic minerals and fabrics. It has been applied particularly to studies of porosity loss in sediments owing to compaction and cementation.